1. Field of the Invention
This invention relates to a process for directly mono-brominating or mono-chlorinating .alpha.,.alpha.-dialkoxyalkyl or .alpha.,.alpha.-dialkoxycycloalkyl ketoximes in the .beta.-position and particularly the production of 3-chloro-2,2-dimethoxycyclohexanone oxime, a useful intermediate in the synthesis of L-lysine.
1. Brief Description of the Prior Art
L-lysine is one of the essential amino acids required in the metabolism of all animals. Since many animal bodies are incapable of producing this required nutritive factor, it must be supplied from an external source such as by the animal and vegetable proteins of a normal diet. Due to the cost and restricted availability of these natural animal and vegetable sources of proteins, synthetic methods for the production of L-lysine are being investigated. Synthetic L-lysine could be used as a supplement in animal diets, particularly in the diets of poultry and swine. Thus, there is a need for an inexpensive, facile and efficient route for the production of synthetic L-lysine.
A synthesis of 3-chloro-2,2-dimethoxycyclohexanone oxime is described in U.S. Pat. No. 3,928,445 (1975), involving the chlorination of 2-alkoxy-3-oximinocyclohexenes and particularly, 2-methoxy-3-oximinocyclohexene. However, the 2-methoxy-3-oximinocyclohexene is a relatively expensive intermediate, and would represent a significant cost factor in a synthesis of L-lysine based on this intermediate.
Chlorination of cyclohexanone oxime with alkyl hypochlorites leads to 1-nitroso-1-chlorocyclohexane and is described in Angew. Chem. internat. Edit., Vol. 7 (1968), pp. 387-88.
The use of a large excess of chlorine leads to chlorinated pyridine derivatives and is described in U.S. Pat. No. 3,830,820 (1974).
U.S. Pat. No. 3,517,047 (Ohno and Naruse, 1970) describes the chlorination of 2-alkoxycycloalkylketone oximes in the presence of trivalent phosphine to form 1-chloro-1-nitroso-2-alkoxycycloalkanes which are intermediates in the synthesis of linear aliphatic omegacyanoaldehydes. However, the chlorination process does not directly produce 3-chloro-2-alkoxycycloalkyl ketoximes.
What is needed and what the prior art does not provide is an inexpensive synthetic route for directly mono-brominating or mono-chlorinating .alpha.,.alpha.-dialkoxyalkyl and .alpha.,.alpha.-dialkoxycycloalkyl ketoximes in the .beta.-position.